1. Field of the Invention
The present invention relates to a dryer for drying various textile goods such as clothes and the like and a method for controlling drying operation thereof and more particularly to, for instance, a rotary-drum (tumbling barrel type) dryer for drying clothes and a method best adapted for controlling drying operation thereof.
2. Description of the Prior Art
In rotary drum dryers for clothes widely used in the cleaning industry, dried air is caused to pass through a rotary drum by an air blower to dry clothes. A peripheral wall of the rotary drum is formed with a great number of pores so that suction air heated by a heat exchanger passes through such pores into the rotary drum and resulting humidified air is discharged through an exhaust duct.
Conventional methods for controlling drying operations of dryers of the type described above are generally divided into the following four types:
1) Time control method for setting a drying time by a timer (as, for instance, disclosed in U.S. Pat. No. 4,338,730); PA1 2) Temperature control method for determining whether the textile goods have been satisfactorily dried or not in response to a predetermined temperature or to variations in temperature (as, for instance, disclosed in U.S. Pat. No. 4,206,552); PA1 3) A method consisting of a combination of the time control method 1) and the temperature control method 2) (as disclosed in, for instance, U.S. Pat. No. 4,412,389); and PA1 4) Humidity control method for controlling operation of a dryer in response to detection of relative humidity (as, for instance, disclosed in U.S. Pat. No. 4,386,471).
Next, problems encountered in the above-described conventional dryer control methods will be described below.